Pure water is always the best option, and between meals is the only option. For the adult a glass of wine, cider or beer with a meal will provide a pleasant alternative. Fruit juices always provide an acceptable alternative, but this is definitely second best to eating the fruit itself.
Any edible fruit can be used as a source of juice, and if prepared at home should be drunk on the day it is prepared. Cartons of fruit juice from the supermarket are a low cost and healthy alternative, provided you limit yourself to one small glass with a meal.
Milk and milk shakes prepared from full milk are always acceptable for children, low-fat milk for adults.